How many and which characters are allowed in .eu domain names?

The length of .eu domain names can vary from a minimum of 2 to a maximum of 63 characters.
The characters which are allowed in .eu domain names are the letters from "a" to "z", the numbers from "0" to "9", and the "-" (hyphen) symbol.

The "-" symbol must not be placed in first, third, fourth (in succession) or last position.